The field of the invention generally relates to a programmable control system such as for a microwave oven, and more particularly relates to such a control system that limits the users who can reprogram the control functions.
Commercial microwave ovens are in widespread usage such as in restaurants and in vending machine areas in business and public buildings. Generally, commercial microwave ovens have a plurality of numerically labelled keypads each of. which is dedicated to a particular control function which is to actuate the microwave oven for a programmed time period. For example, the "1" keypad may activate the microwave oven for 12 seconds, and instructions might indicate that this keypad should be used for pastry rolls. Also, the "2" keypad may activate the oven for 22 seconds, and instructions might indicate that this keypad should be used for small sandwiches. Further, the "3" keypad may activate the microwave oven for 42 seconds, and instructions might indicate that this keypad should be used for hamburgers and pies.
The owner of a commercial microwave oven may want to reprogram time periods associated with various keypads for any one of a number of reasons. For example, he may add to his vending machines a food product that requires a cooking time period that is not already provided as a control function of one of the present keypads. Also, he may receive complaints that a particular food category comes out too hot or too cold, and it may be necessary to adjust the cooking time either down or up.
As is well known, it is important that the general users not have access to the feature of reprogramming the time periods associated with the keypads. If such were the case, users could inadvertently or intentionally tamper with the cooking times thereby creating a significant problem for the owner of the commercial microwave oven. Accordingly, prior art commercial microwave ovens have complicated procedures for reprogramming the time periods, and these procedures may involve an expensive service call so that the control panel can be removed by a trained technician.